Code review comment for lp://staging/~rvb/storm/storm-0slice-bug-872086

Without changing the code, this test passes:

    def test_result_set_count_sliced_none(self):
        result = self.Person.select()
        sliced_result = result[None:None]
        self.assertEquals(len(list(sliced_result)), 2)
        self.assertEquals(sliced_result.count(), 2)

I think the limit and offset parameters being None is a case that is already taken care of by the code (also, result[1:None] and result[None:4] behave as expected).